Fiber optical liquid level sensor under cryogenic environment

This paper reports a preliminary experimental investigation and characterization of an optical fiber-based liquid level detection system for applications in cryogenic environment. The sensor system comprises a multiplexed array of point liquid probes. Two different designs of the probe were fabricated and tested. Probe tests were conducted in water–air, liquid–gas nitrogen environments. The multiplexing of multiple liquid probes using an optical time domain reflectometer (OTDR) device was successfully demonstrated. In addition, response time of the liquid probe was measured and compared experimentally.